Drilling machine



1 21, 1944- R. B. MENTZER 12,363,136

DRILLING MACHINE Filed June 11, 1941 2 Sheets-Sheet l INVENTOR. RALPH 5. Mf/VTZEE BY ATTORNYS.

Nov. 21, 1944. B. MENTZER DRILLING MACHINE 2 Sheets-Sheet 2 Filed June 11, 1941 INVENTOR. RALPH BMENTZEE ATTORNEYS.

Patented Nov. 21, 1944 Ralph Bender Mentzer, :Lancaster, Pa., assignor to Hamilton Watch Company, Lancaster, Pa.

Application June 11,1941, Serial No. 397,566

. i i 14 Claims. This invention relates to automatic drilling machines and has for its object the provision of means for and method oi automatically accomplishing delicate drilling work.

Another object is to provide improved means and method of drilling jewels. l

Another object is to provide automatic means adapted to bring about a plurality of relative approaches and retreats of the drill and workpiece during a single drilling operation.

Another object is to provide automaticmeans adapted to bring about a series of separate contaots, of increasing length, between the drill and the work, during a single drilling operation.

Another object isto provide automatic means adapted to bring about a plurality of relative approaches and retreats oithe drill and workpiece during a single drilling operation, with the extent of the approaches and the length of time between the end of the approach and the beginning of the retreat progressively increasing.

Another object is to provide an automatic drilling device having means constantly tending to hold the drill and workpiece in contact and means adapted .to periodically overcome that tendenc duringa single drilling'operation. i v

. Another object .is to provide automatic means adapted to quickly bring about a relative approach between the drill and workpiece from a relatively great separation to a relatively small separation and thereafter a plurality of relatively .slow approaches from the small separation position, .all during a single drilling operation.

Other and further objects will be clearly apparent from the following specifications and from thedrawings. v i

Fig. I is a plan viewof the device embodying this invention;

Fig. II is a side elevation .of the device illustrated in Fig.1; i 1

Fig. 111 is an end elevation of the left portion of the device as illustrated in Fig. I;

Fig..IV is an end elevation of the right of the device as shown in Fig. I; i

Fig. V is a section of the drill holder unit;

Fig. VI is a section of the work holder-unit;

. Fig. VII is an elevation of the member 10, of

Fi II;

Fig. VIII is an end view of cam ll, Fig. II; and

Fig. IX is a longitudinal central section of cam I4, Fig. II.

The drilling of small holes particularly in small relatively brittle'objects such as timepiece jewels has been a diflicult and delicate operation, requiring the constant and careful attention of a skilled portion operator during its performance. The approach V of the tool to the work, the pressure applied and the permissible length or actual drilling time at one stretch during the various stages oi. a single drilling operation, must-be carefully and expertly governed and carried out. This makes for a time consuming and expensive operation.

operation.

The device of this'invention obviates the prior art difllculties by providing automatic means for carrying out all of the diflicult and delicate steps of the operation, and is such that asingle, un-

skilled operator may efficiently run'sev'eral machines simultaneously and accordingly a considerable savings in time and operation expense is The automatic drill of this invention is particularly directed to and adapted to the drilling of smallpivot holes in watch Jewels. For purposes of illustration and description. the invention is explained in connection with a Jewel drilling machine. However, it should be clea'rlyunderstood that. this invention may be used in any drilling In order to impart strength and accuracy to the necessarily small diameter drill, it is rotated at a fast rate. The jewel is also rotated but at a slower rate, and abrasive is placed on the jewel and allowed towork into the hole being drilled.

The Jewel is first set up in a holder separate from the drill and approximately concentric with the holder. The holder is then mounted in the drill concentrically with the work holder shaft.

In this way the jewel is drilled at its approximate center and accordingly the procedure of later for ng the periphery of the Jewel concentric with the drilled hole is not only made easier and simpler, but less jewel stock is wasted than it the hole had not been-drilled with such concentricity. i I

Since the drill is delicate and the jewel hard, relatively slow approach of the drill to the work is eiiected. It is also necessary to keep the drill in contact with the jewel only a short period of time at first, in order to get the hole started without breaking the drill. As the drilling proceeds, the drill may be kept in contact with the regard for jewel for progressively longer periods, as the hole gets deeper, and this is all accomplished auto matically. The pressure of the work against the tool is made steady and resilient during its permitted periods through the action of a weight on a resilient lever, constantly tending to urge the work against the tool but periodically overcome by cam action.

The work is accordingly moved toward and away from the tool a number of times during the drilling action and allowedto remain in contact with "the tool between these motions for'progressively increasingly periods of time as the hole gets deeper. It is not usually desirable to drill the hole all the way through the jewel, since one side is to be cupped in a later operation. Accordingly the extent of the drilling is automatically controlled to prevent excess drilling through material which is to be removed subsequently.

The whole device is automatic and needs only the depression of a single starting lever to start drill and work rotation as well as cam and feed operation.

The device embodying this invention comprises three units adapted to work together. These are, a work holder unit, atool holder unit, and a control unit. The work holder unit includes a plate member 39 and a cap member 40, between which the work is adapted to be held. The tool holder unit includes a tool chuck 21, and the control unit includes cam I 4, and feed screw I5.

This unit construction permits the several units to be removed or replaced separately and is an advantage when it is desired to repair or replace any of the parts of the device.

g The work is rotated at a relatively slow speed as the plate member 39 and cap member 40 are rotated through the action of the motor 5 and the .control unit by the agencies of the pulleys 6 and 'I and the belt 8.

The drill 26, held in the tool chuck 21, is adapted to be rotated at a relatively high rate of speed through the action of continuously traveling belt I on the drive pulley I2.

The motor also operates a feedingarrangement for bringing the work holder into operative relation with the drill 26. This arrangement comprises mainly a-cam lever I3, a cam I4 and a feeding screw I5. The feeding screw I5 is driven by the motor 5 through the worm gear -I6 and the cam I4 is so contoured as to cause the work holder to be moved towards and away from the drill 26 in such a manner that the work holder is moved relatively slowly towards the tool holde and relatively quicklyaway therefrom several times during the operation of drilling one jewel. This method of operation is used since the drill used in this invention is of very small diameter and quite delicate and brittle so that the relative approach between the drill and the work must be slow and the drill must be held against the work only" calculated and relatively short periods of time. The drill is then removed from the work before the operation is finished through the action of the cam I4 and cam lever I3 in order to permit abrasive to enter the partially drilled hole in the jewel and to prevent damage to the drill, and then the drill is again brought into contact with the work. The work holder is urged toward the drill by means of a weight I1 (Fig. I) which is adjustable longitudinally on a lever I8. The lever I8 acts through the work spindle operating lever I9, and is preferably formed of resilient material so that the jewel is held against the drill with a steady, yet resilient, pressure.

The device of this invention as illustrated in the drawings shows the various mechanisms and parts in their out of operation position, that is, with the device ready to start the drilling operation. The traveling belt I0 is constantly moving and rotating the idler pulley II but the drive pulley I2 is not yet in operation so that the drill spindle is stationary. r

shaft .2I and pulley I2.

The drill spindle unit is illustrated in ma. v and comprises a housing 20 in which a hollow shaft 2| is rotatably. mounted at each end thereof on ball bearings 22. The shaft 2| has an exterior thread 23 at its upper end by means of which the drive pulley I2 is mounted thereon for rotation therewith. There is a second hollow shaft 24 mounted in the hollow of the shaft 2I and so mounted as to rotate with the shaft 2I. The shaft has a head or finger piece 25 at one end. thereof which extends beyond the hollow The hollow of the shaft 24 is adapted to contain the drill 26. A chuck member 21 is threaded to'the lower end of the shaft 24 and the drill is held in operative position by jaws '28 of this chuck. The chuck 21 may be loosened and the jaws 28 opened by turning the finger member 25, so that the drill may be moved to a new position in the chuck 21 and the jaws 28 thereafter clamped on the drill. The drill is normally a relatively long-member, and when its working end becomes worn, it is drawn through the chuck 21 and broken ofl to present a fresh drilling portion. The housing 20 is provided with anoil cup 29 near its top and an oil drain 30 near its base so that the bearings 22 are constantly properly lubricated.

The drill 26 is positioned in the chuck 21 so that its working end lies at a point in relation to the work holder which is effectively zero drilling position as governed by the contour and position of the cam I4 and feeding screw I5. The adjustment of the drill to this zero position is effected through the use of a stop member 3|, see Figs. I, II, and III. This stop member 3I is in the form of a substantially horizontal plate which may be swung into position between the drill and the work holder, by means of a handle 34, about its pivot 32 which is mounted on a bracket 33 supported by the housing of the work holder unit.

The drill is therefore moved through the chuck 21 until it contacts the plat 3|, the jaws 28 of the chuck are then closed upon the drill through the movement of the finger piece 25, and the plate 3I is thereafter pivoted out of the way of the drill. As well as acting as a stop and positioning member the plate 3I also acts as a protector for the work in the work holder. When the drill 26, after a'certain period of operation, becomes under size for ashort portion of its length, this portion is broken off, usually with a pair of pliers, in order to present a new and fresh portion of the drill to the work. With the plate '3I in position between the drill and the work there is. no possibility of this small broken 011 piece of drill getting in the work holder or in a partially drilled hole in the work and causing damage.

The jewel to be drilled is held in a separate holder which in turn is held between the plate 39 and cap 40 in the work holder unit. As illustrated in Fig. VI the work spindle 36 is rotatablysupported in a sleeve 31 which is mounted in the work supporting unit. The spindle 35 is driven through the pulley I which is rigidly attached thereto. In order to permit the insertion of the jewel holder in the work holding unit a through one of the openings 46 in the sleeve 38. The cap member has an initially centering portion 4| which is adapted to fit within a portion of the jewel holder so as to locate the holder substantially concentrically of the spindle 36. The centering of the jewel holder is completed when the bevel of the plate member 39 is forced against a bevel of the jewel holder to clamp the jewel holder between the plate 39 and the cap 40.

The plate 39 and cap 48 are separated to Permit the insertion of the jewel holder therebetween through one of the Openings 46 by the action of a cam member 42, see Figs. 11 and III on the lower end of the shaft43 which is positioned within the spindle 36. The shaft 43 rotates with and is movable longitudinally with respect to the spindle 36 and movement of the shaft 43 longitudinally against the action of spring 44 causes the sleeve upwards about its pivot 59.

,38 to move with respect to the spindle under the action of the cross pin 45 so as to separate the cap member 40 and the plate member 39 sufliciently to permit the insertion of the jewel holder therebetween through one of the openings 46.

The spring member 44 acts downwardly on a shoulder 41 of the shaft 43 and upwardly on a shoulder 48 of the spindle 36 so that the plate 39 and the cap member 48 are normally urged to.- ward each other. I

The cam member 42 is operable to lift the shaft 43 and separate plate 39 and cap 40 through its association with a horizontally disposed lever 49 pivotally mounted at 56 on the housing of the work holding unit.

The cam 42 is so formed and mounted as to straddle the lever 49 so that when this lever is moved about its pivot 50 by means of the handle 5| the cam is correspondingly caused to move against the lower end of the shaft 43 and cause the shaft 43 to ride on this cam 42 to move the shaft 43 up or down as desired.

The spindle 36 is normally kept from rotating through the action of 'the detent 52 upon a sleeve 53 which is rigidly secured to the spindle as. The

sleeve 53 is provided with V slots 54 into which the tapered end 55 of the detent 52 is forced by a spring 56. The spring 56 and detent 52 are mounted in an opening in the work holder housing. 'The spindle 36 and accordingly the work holding assembly are; by this arrangement, located in such a position as to present, when stationary, one of the openings 46 at the front of the achine to facilitate the insertion of the jewel holder. i

The operation of the device as a whole is started by downward pressure on the finger piece 51 of traveling belt I8, the motor 5 is started and caused to rotate the work spindle 36, and the cam l4 and feed gear I5 are brought into action to move the worktoward andaway from the drill 26.

The spindle 36 is released when the detentv 52 is moved out of contact with the sleeve 53 against The drill 26 is brought into rotation upon the depression of the starting lever 58 by the release of the angle lever 64 from its contact with the cam member. '65. The angle member 64 is pivoted on the housing of the drill spindle unit at 66 and has one leg 61 which supports the idler pulley I I and another leg 68 which is adapted to contact the cam so as to hold the idler pulley II away from the drive pulley I2 against the action ofthe spring 69.

The cam 65 is mounted on a plate I0 for sliding movement vertically of the housing ,of the drill unit by means of bolt; II5 located in elongated openings [I6 in the plate 16, and is connected the idler pulley I I towards the drill driving pulley the action of the spring 56 by means of a cam member 69 which is moved downwardly upon'the depression of the starting lever 58 through its connection III therewith. The cam member 69 moves in a slot 62 in the detent 52 to force the detent 52 away from the 'sleeve 53 so that the spindle 36 is then free to rotate. The spring 63 I2 so as to cause the belt I0 to act upon the pulley I2 to drive the drill 26. Releasing of the starting lever 68 causes the cam 85 to move upward, under the action of spring "63 which encircle; the continuation H3 of the plate I0 and which presses upwards against the plate I8 and downwards against the housing H4. againstthe leg 68 of the angle piece 64 and separate the belt I!) and the drive pulley I2 and consequently stop the drive of the drill.. The belt I6 is under such pressure against the idler pulley II that the belt will follow the idler as it moves away from the drive pulley I2.

The idler pulley II is mounted on the angle piece 64 by mean; of a bearing screw 1| and operates on hearing I2 and is provided with a cap member 13. e

The motor 5 is brought into operation upon the depression of the starting lever 58. This is accomplished through a spring member I4 mounted on the lever 53 and pressing against the contact of the starting switch [5 normally holding the switch in open position. The downward movement of the lever 58, relieves the pressure of the spring I4 on the switch contact and permits the circuit to close. thus starting the motor. It will also be seen that when the lever 58 is raised, the spring again exerts pressure upon the switch contact and opens the circuit, thus automatically stopping the motor.

The spindle 36 of the work holder unit is adapted to be raised and lowered so as to move the work toward and away from the drill 26 under the action of lever I9. The lever I9 has one end fixedly mounted on a horizontal shaft 16 pivotally mounted in the housing II4.- The other end of the lever is is adapted to move the spindle 36 upward and downward through the action of a pin 11. mounted in the end of the lever I9. upon the bushing 18.01 the sleeve 53. The shaft I6 is constantly urged about its axis by means of the lever I8 andthe weight I I thereon in such a direction as" to urge the work holder upward towards the drill. The motion of the work holder toward and away from the drill is. however, controlled by the cam shaft I3 which also has one end fixedly mounted on the shaft I6. The cam shaft I 3 at its other end has'a cam nose I9 which bears on the camlI4 and through the connection with the shaft I6 andthe fixed connection of the arm I8 with the shaft I6 the weight I! acts not only to urge the work holder upward but also to urge the cam nose I9 against the cam l4.

Accordingly, the cam nose [9 is adapted to follow the contours of the cam I4 during rotary and longitudinal movement of that cam except in some instances during the operation of the device. The card I 4 is so shaped that at certain portions thereof, namely, the low points of the flutes 8|, see Figs. I, II and VIII, the cam nose I9 will not be in contact with the cam because of the fact that the work is in contact with the tool under the pressure of the weight I I. The cam I4 has a two'way action. As it is moved longitudinally of its own axis the cam nose 1.9 is caused to travel down the face 82 of the cam and move the work at a relatively rapid rate to a point, as represented on the cam at 83, just short of being ,in contact with the drill. Meanwhile the cam 14 is rotated so that the nose 19 moves circumferentially thereon in and out of the flutes 8| causing the work to move towards and away from the drill. As the cam nose 19 moves down the gradual slope as indicated at 84 the work is moved gradually towards the drill and then as the cam nose moves up the sharp slope 85 of the cam I4 the work is quickly dropped away from the drill. a

An imporant feature of this invention is the combined operation of the weight I1 and the cam I4 in their control of the movements of the work with respect to the tool.

The nose .19 of the cam lever I3 is urged against and caused to follow the contours of cam I4 through the action of the weight I1 which is mounted on resilient lever I8 in such a way as to tendto rotate shaft I6 and move lever I3 down, and lever I 9, and accordingly the workholder, up.

Thus; when the work is not in contact with the drill, it will be moved in accordance with the movementof the nose I9 on the cam I4, so

that the action of the cam most of the time is tokeep the work away from the drill. When the nose 19 moves into one of the depressions 8| in the cam I4 the work is brought into contact with the tool. Since the cam keeps moving, its rotation leaves the cam nose I9 temporarily hanging'in the air between the high points of the cam. This is so since the lever I9 is prevented from moving upward by the contact of the work and the tool and accordingly the lever I3 is prevented from moving downward.

In this position the work and the tool are urged against each other with a force provided by the weight I! and a resilience provided by the weight lever I8. The work and tool are thus permitted to contact each other for a length of time determined by the speed of rotation of the cam I4 and the pitch and speed of rotation of the feed'screw I. As the cam rotates, the cam lever nose "I9 is again picked up on a shoulder of the cam as at 85 in FigaVIII which, as the cam continues to revolve, lifts'thenose I9 and moves the work away from the tool against the action of the weight I'I. grooves 8| of cam I4 are substantially V shaped with the small point of the V near the starting position of the cam with respect to the starting of the drilling operation. This V slot or groove in the cam becomes wider and deeper as the drilling proceeds. The depth of the groove 8| permits the work to be moved further and further upwards as it progresses and as the hole is drilled and the width of the groove permits the drill to stay in contact with the work longer and As is shown in Fig. II, the

longer periods of time as the drilling goes on and the hole gets deeper.

The double action of the cam is set into operation when the starting lever 58 is depressed. The

housing of the control assembly has a bell crank lever 86 pivotally mounted therein at 81. The lever 86 has one leg pivotally attached to a'connection shaft 88 which is also pivotally attached to the starting lever 58. The other leg of the bell crank lever 86 is connected through a. yoke member I09 to a collar I III which is movable longitudinally of and is mounted on the supporting shaft 89 of the cam I4 and'feed screw I5. When the starting lever 58 is depressed the bell crank lever 86 is moved about its pivot 81 and causes the cam I4 and the feed screw I5 to be moved along their supporting shaft 89 against the action of the spring 90 which is also mounted on the shaft 89. The shaft 89 is rotated by the motor 5 through the worm gear I6, and the feed screw I5 and cam I4 are so keyed to the shaft 89 as to rotate with it and be movable along it.

The starting lever 58 supports a bracket 9| in which a headed pin 92 is vertically positioned. The pin 92 is of such a contour as to relatively closely and slidably fit within the opening between the bracket 9| and the lever 58, andthe head of the pin 92 is of such a size as to prevent the pin from dropping through the opening formed by the bracket 9|. The pin 92 is urged downwardly by a spring member 93 which is mounted on the starting lever 58 and presses downwardly against the head of the pin 92.

The pin 92 has at its lower end a finger 94 which is adapted to fit within and' travel along the threads of the feed screw I5 upon the rota tion of the shaft 89. When the lever 58- is depressed the cam I4- and feed screw I5 are so moved along their axis 89 and the finger 94 of the pin 92 is so moved dow'nwardly as to bring the'finger 94 into contact with the feed screw I5 so that continued rotation of the feed screw I5 causes it and cam I4 to be drawn along their shaft 89 against the action of spring 90, because of the riding contact of the finger 94 with the feed screw I5, and accordingly the cam nose 19 travels over the contours of the cam I4 longitudinally and circumferentially as the rotation of. the shaft 89 continues.

The spring 93 presses downwardly on the pin 92 so that in the event the finger 94 does not-immedlately fall within the thread of the feed screw I5, the pin 92 may be pushed upward against the spring 93 until such time as it does fall into the thread. This prevents breakage or damage to the finger 94 or the-threads of the feed screw I5.

The lever 58 is maintained in its depressed or operating position by means of a holding lever 95 which is pivoted to the housing of the control assembly at 96. A holding. bracket 91 is mounted on the starting lever 58 and when the starting lever 58 is in its raised position, as shown-in the drawings, the holding lever 95 is pulled against the bracket 91 under the action of spring as which has one end attached to the starting lever.58 at .99 and the other end attached to the holding the spring 98 pulls the holding lever 95 so as to cause the surface IDI of the bracket 9'! to be held I02 of the holding ver 58 is prevented beneath and by the surface lever 95. Thus the starting le While the starting from moving upwardly about its pivot 59 under the action the spring at.

f lever 58 is held down by the holding lever lltheiinger 94 travels; in the threads or the-.ieed screw l5, thus causing the drilling toproceed. The extent of the drilling,

that is, the length oftime which it is allowed to continue, may be automatically set by means of the stop pin I03 This Pin is adjustably mounted on the holdinglever 95 and is adapted to con- "tact the face I04 of the cam when the camhas been moved along. its. ,axis'tow'ard thefinger 9d the desired amount. -u a .When the pin I03 contactsthe surface I04 of the cam I4, continued movement of the cam along its axis will push the holding lever 95 about its pivot 96, and separate the holding surfaces IOI operation; 1O

3. In a device of the character rdescribed, 'a cam member mounted for simultaneous trotary and axial movement onits own longitudinal axis, and a followerffor said ,camflmernber, said cam being adapted to cause its follower to periodically move from the same effective zeronposition' in progressively increasing lengths of movementand and I02, of bracket 91 and,holding lever 95 respectively. The starting lever 58 will then rise under the action of the spring 63. The drilling operation will consequently stop since the spring member." again presses, on the contact of the switch 15,,opening the motor circuit and stopping the motor 5. Also, the ,upward movementiofthe starting lever 58 moves the cam 65 upward against the leg 58 of the angle piece 64 so as to move the idler pulley II and the belt I0 away fromthe drive pulley I2, thusstopping the driving of the drill. a W 1. a

The motor 5, being stopped; the work holder spindle is no'longer driven, and theupward movement of the starting lever58 moves the cam 50 out of contactwith the pin 52 .which is accordingly again pressed against sleeve 53 underlthe action of the spring 55 and the coasting of the spindle 36 turns the sleeve 53 until one of the V, slots 54 therein is'contacted by the end 55 ot the pin 52 so as to hold the work holding spindle 35 in one of the loading positions as determined by the positions of theopenings 46. This is possible since the work spindle is no longer driven by the motor. Also the cam I4 and the feed screw I5 are moved back to their original starting position, which is shown in Fig. II, under the action of the spring 90, as soon as the pin member 94 is removed from the threads or the screw member I5 by lifting the starting lever 58 and,v as they are no longer urged along their axis through the action of the bell crank lever 85.

When the cam member I4 and feed screw l5 are snapped back into starting position by the spring they are stopped by means of a resilient type washer I05 or material such as leather, or other suitable cushioning means,

Emergency stop means is provided in the form of a rod I09 which is suspended beneath and along the length of the starting lever 58. The rod I05 is operable through a push button I01, adjacent and below the starting button 51. Pushing the button I01 causes the rod I05 to engage the holding lever 95 so as to separate the about a plurality-of periodi': contacts ofsaid drill to periodically rest for progressively increasing periodsof time. i

4. In an automatic drilling machine, aidrill a" workholder," and control means adapted to brin with work in said; workholder during a single drilling operation, jandwith said contacts progressively increasing in duration of contact,said control means including a cam adaptedto move" along, and rotate about its longitudinalaxis, and a feed screw adapted to. aid in moving said cam along said axis. 5: In an automatic axis; anda feed screw adapted to aid in movin said cam along said axis, and resiliently supported weight means adapted to resiliently urge work against said drill during-the periods of said contacts.

6., In an automatic drilling machine, a drilling chuck, means for revolving said chuck, a drill rod adjustably carried in said chuck, a work holder having a jewel carriedthereby, a vertically movable rotatable support for said work holder,

means for forcing saidlewel into a predetermined number, of periodic contacts with said drilling rod, means for progressively increasing the duration of contact of said periodic contacts, and' means for stopping the drilling operation upon completion oi; the predetermined number of contacts.

holding surfaces I0] and I02 whereby'the starting lever 58 will move upwardly and the machine will stop. The emergency lever I06 is held in its normal inoperative position by spring member What I claim is: k 1. In an automatic drilling machine, a drill, a

workholder, means adapted to bring about a plurality of periodic contacts of said drill with work in said workholder during a single drilling operation, and means for progressively increasing the duration of contact of said periodic contacts.

2. In an automatic drilling machine, a drill, a

said contacts.

workholder, said workholder adapted to hold the 7. In an automatic drilling machine, a drilling chuck, means for revolving said chuck, a dril1 rod,

,iadjustably carried insaid chuck, a work holder having a jewel carried thereby, a vertically mov able rotatable support for said work holder, a rotatable cam mounted for longitudinal movement, a pivoted lever bearing upon the cam at one end and engaging the rotatable support at the other end, means for resilientlyforcing said support into engagement with said lever whereby said cam causes the rotatable support to be raised and i H lowered to bring the jewe1 into periodic contact, with said drill, means for progressively increas ing the duration of contact of said periodic con tacts, and means for controlling the number of 8. In an automatic weight, a cam normally urging said workpiece into contact with said drill, having a series of drilling machine", a ,driILIaE workholder having work supported therein, control means adapted to bring about a plurality of. periodic contacts, of saiddrill with said work ldul' ing a single drilling operation and with said con-1 tacts progressively increasing in duration of contact; said control means including a cam adapted 3 to 'ove along, and,rotate-about,,its longitudinal drilling machine a rotatable drill formed of an unsharpened iron wire, a drilling compound, a work support carrying a work piece mounted for vertical movement, a

" "d sconceupstan'din'g projectionsroaid projections tapering rrom a' base to an' apex; ionsitudina'liot said cwmans tbr rot'ating and-"moving said cam' longitudinally; a; -lever contazotinggjtne projections oriupstanding'projections; said projections taper:- ing efron'r -ai baseftoioxilapex longitudinal of'said: camwu-rtace; meansfor rotating and moving; said cam longitudinally, w lever contacting the pro iectionaomaid cEmvsUrIice -"an'd controiding-i the o" said worlnsupport; .thelongitudinali and iting the drilling operation.

ing t to" claim 9 the-drilling: limiting means:- com-- prising; 9; stop controlled? by the longitudinal movement ofthercam.

11:. In an'wautomatic drilling machine having.- a

planeyap arm, 35'

means formoving" said workpiece: toward! and drilling machine accordmeans: to stop thevdriiiin completion: of a predetermined number-scream;

v holdez toward and away from saidlidrili: and 1nto-- contaotewitli" drilhmeanaior progressivelyincreasing-median V tiomofcontact:betweenu saidiiworkpiecerandfisaid'i drill during a single: driliing operation endsfstomg: operationiz uppm thee contacts.

12. In an automatic; drimngmachinewhavingia: workpiece: movable: in a vertical;

away from said drilf & camiucontrollmg'i'thes vemtical-movem'ent of said workpiece-andimeans'con+- trolling: the: movements of said com to. progreszslvely increase the? duration of: contact: between-a saidzdrill and saidiworkpieceduringraisingiscdriit ingioperation.v

13". In an automatic: l'iriliing v mecl'iine, an drill):

aworkholder having: work mounted; tlierein;.. means adapted to. bring-ab'out a.tpiurazlity 'omele tive movements between saidrdriliian'dr saidi'work 14.1.1111 an au having-work piece supporting'rmeansggsaidworltewei v during a single drilling" operations:

7 RALPHLBENDEREMEHJTZER; v 

